Need Help HP DM3 (DM3-1130us) Laptop will not power on. No power at all except for light on a/c jack

Unfortunately it is difficult to troubleshoot this type of issue. The majority of the time when the computer wont power on with the same symptoms you described, the power supply board is faulty. Most of the time if the motherboard is bad it should at least turn on or so some signs of life. Like I said, this is most of the time. Sometimes it could do exactly what your experiencing. I would suspect the power supply board has failed since you are not receiving any sort of lights, sounds, etc.

You could check the motherboard for swollen capacitors or loose solder joints but sometimes you wont be able to find anything.